Miss Winters is a dancer with the Tommy Dorsey Orchestra and is asked to secretly transport a prototype magnetic mine to Puerto Rico. She thinks that she is working for the US Government, but fails to see why she would be involved. The enemy agents got the plan from a pulp novel written by Kibble, who is also on the ship and falls for her. But then she overhears his new novel and believes that he is talking about her. So when they leave the boat, she ignores him, but somehow, the bags get switched and he gets the magnetic mine - which she must later retrieve. It is mainly a Tommy Dorsey showcase with Sinatra singing - Powell dancing - and a small plot.